It is known that chelating agents such as ethylenediaminetetraacetic acid (EDTA), 1,3-diketones and thiosemicarbazides, among others, form chelates with metal ions. However, of the known chelates few have been shown to exhibit fluorescence and more particularly, fluorescence produced by X-ray irradiation.
It is known that certain compounds such as for example fluorescein, coumarin, rhodamine and the like, contain groups which exhibit fluorescence when excited with incident light. It is also known that a few of these compounds or dyes, such as fluorescein isothiocyanate, have been used in analytical techniques for the determination and measurement of biological compounds of interest. However, there are various disadvantages associated with the prior art dyes that are employed in analytical techniques involving fluorescein. The fluorescence produced by conventionally employed dyes have limited excitation/emmision spectra, low quantum yields, high background fluorescence and, most importantly, such dye complexes are not permanent but fade and bleach.
Accordingly, one or more of the following objects will be achieved by the practice of the present invention. It is an object of this invention to provide 2,6-diureadopyridines and certain transition metal ion chelates which exhibit stable, fluorescence. Another object of this invention is to provide novel chelates which will exhibit distinct fluorescence exitation and emission spectra, corresponding to that of the specific metal ion that is chelated and wherein the chelates themselves are stable. It is a further object of the present invention to provide a process for simply and rapidly producing complexes of 2,6-diureadopyridines and metal ions which fluoresce when they are exposed to incident light. It is also an object of this invention to produce novel chelates of 2,6-diureadopyridines and transition metal ions. A further object of this invention is to provide chelates of 2,6-diureadopyridines which exhibit fluorescence upon X-ray irradiation. A still further object of this invention is to provide a method of X-ray imaging development utilizing the chelates of the present invention. A still further object of this invention is to provide chelates which will exhibit distinct fluorescence exitation and emission spectra corresponding to that of the specific metal ion which is chelated with the diureadopyridine when such compounds are exposed to X-ray radiation. Yet another object is to provide chelates of metal ions which are stable and which exhibit fluorescence without fading or bleaching. These and other objects will readily become apparent those skilled in the art in the light in the teachings set forth.